Femur (Thigh Bone) ‒ Section

**Gross anatomy of a bone** The structure of a long bone provides the clearest view of its components. The first section, the diaphysis, is the tubular shaft that runs between the proximal and distal ends of the bone. Inside the diaphysis is a hollow area known as the medullary cavity, which is filled with yellow marrow. The walls of the diaphysis consist of dense, hard compact bone. The second, wider section at each end of the bone is called the epiphysis, which is filled with spongy bone containing red marrow in its spaces. Each epiphysis meets the diaphysis at the metaphysis, a narrow area that contains the epiphyseal plate (or growth plate), a layer of hyaline (transparent) cartilage in growing bones. Around the ages of 18–21, the cartilage is replaced by osseous tissue, and the epiphyseal plate becomes an epiphyseal line as bone growth stops. The medullary cavity is lined with a delicate membrane called the endosteum, which is where bone growth, repair and remodeling occur. The outer surface of the bone is covered by a fibrous membrane called the periosteum, which contains blood vessels, nerves and lymphatic vessels that nourish compact bone. Tendons and ligaments attach to bones at the periosteum, covering the entire outer surface except where the epiphyses form joints with other bones. In these regions, the epiphyses are covered with articular cartilage, a thin layer of cartilage that reduces friction and serves as a shock absorber. *LICENSES AND ATTRIBUTIONS CC licensed content, Shared previously, Donna Browne, Skeletal System Module 4: Bone Structure, Authored by: OpenStax College. License: CC BY: Attribution. License Terms: Download for free at http://cnx.org/contents/5Ofth9yh@2/Skeletal-System-Module-4--Bone* ## Keywords section of femur blood vessel articular cartilage bone marrow tissue dense pulp cavity long periosteum